Effect of copper introduction on the properties of micro-arc oxidation coating on powder metallurgy aluminum disk

Abstract

Powder metallurgy (PM) is a process technology utilizing metals as raw materials that are shaped and sintered to create metallic materials. Micro-arc Oxidation (MAO) is a surface modification technique that improves the surface properties of metals by forming a dense oxide coating on the metal surface. In this study, aluminum‑copper alloys were prepared by introducing copper to PM aluminum disk, and the alloys were treated with MAO. During the PM process, Cu atoms diffuse into the Al particles, filling the gaps in the Al particles and improving the interface bonding strength of the particles. The CuAl2 phase is also generated, which improves the mechanical properties of the alloy. During the MAO process, the addition of Cu filled up the pore defects of the PM Al disk, and a complete and dense oxide coating was formed on the surface of the alloy. The MAO coating was characterized by scanning electron microscopy and X-ray diffraction. The mechanical strength of the alloy was evaluated by metal bending tests. The wear resistance of the coating was evaluated by tribological tests and the wear marks after friction were characterized by metallographic microscopy and energy dispersive spectroscopy. The hardness of coating was evaluated by microhardness tester. The corrosion resistance of the coating was evaluated by electrochemical corrosion tests. The test results show that the substrate after the introduction of Cu by PM and treated by MAO has high strength, high hardness, low coefficient of friction, high wear resistance and high corrosion resistance. It effectively improves the mechanical properties of the alloy, improves the performance of the MAO coating, and improves the service life and application range of the metal.